Behavioral outcome of posterior parietal cortex injury in the monkey

Recent studies from our laboratory have characterized the response properties of trigeminal nociceptive neurons located in the posterior parietal cortex of awake monkeys, particularly in the rostral portion of the inferior parietal lobule and parietal operculum within the lateral sulcus. The stimulus intensity-response functions of some nociceptive neurons were significantly correlated to the stimulus intensity-escape frequency functions. The present study provides evidence that trauma to the posterior parietal cortex alters pain sensibility to the contralateral face. Although thermal pain tolerance was dramatically altered, the discriminative aspect of thermosensitivity may have remained intact. Our results complement the recent findings of clinical studies concerned with pain and damage to the posterior parietal cortex and of experimental studies concerned with painful stimulation and changes in regional cerebral blood flow. The role of the posterior parietal cortex in nociception and pain is discussed in relation to the first somatosensory area and to unilateral spatial neglect (inattention).